Self-locking screw



Aug.. 30, 1932. l c. G. oLsoN 1,874,595

SELF LocxING scREw Filed nec. 2e. '195o Patented Aug. 3o, `1932 y lJ'Nll'rF.nu STATES PATaNn oFFlcE CARL G. OLSON, F CHIUAGO, ILLINOIS, ASSIGNOR T6 SHAXEPROOF LOCKiWASER COM- IPANT, OF CHICAGO, ILLINOIS, A CORPORATION'OF DELAWARE SELF-LOCKING scanw Application filed December 26,1930. Serial No. 504,765.

'My I' invention relates generally toK seZlflocking screws, and more particularly to devi c`es of the set screw type, wherein the exwork piece.

' It is one' of the primary objects of my invention to provide a self-locking screw which is more positive' and effective in its binding actionthan screws of this general the companion surfaces of the threads in the t e which have been, employed heretofore.

. ore specifically, it sfan object of my invention to provide a scew in which substantially the entire threadsurfaces thereof co-act with the companion threaded surfaces of the work piece to frictionally resist an unscrewing force. v 6 Still more specifically, my invention. conl templates thelprovision of ascrew in which v.the threadsnormally occupy aspiral position, so that when the screw is inserted withf in a threaded aperture of a work piece, these spiral external screw surfaces will friction-l ally enga e the companion thread surfaces of said wor piece. 2 u

' Numerous other objects and advantages will be more apparent from the following detailed description when considered in connection 4with the accompanying drawing,' wherein- A Y Figure lis a plan view of a set screw constructed in accordance with the vteachings of my invention and provided with 'a single spiral external thread surface;

.Figure 2 is a. side elevational view of the device shown in Figure 1; ',j

Figure 3 is a plan view of amodif'ed or alternative form of scr'ew, in which the body of the screw presents a pair of threaded sections, each of -said sections having externall formed screw,.,which is provided from the other screws which are provided i with central apertures extending completely therethrough. terna] ysurfaces of the screw are adapted to automatically'and yieldingly bear against Referring now to the drawing morein detail wherein like'numerals 'have been employed to designate similar parts through the various figures, it will be observed thaty one embodiment of the invention resides in the provision of a sc rew,v which I have des- Y ignated generally by the numeral 10 in Figw Y ures 1 and 2. This screw is formed with a central aperture 12 which extends through-- out the length ofthe screwpand it will `be noted that the sides of the screw are tapered,

the smaller end being presented at the lower I end of the screw, and the larger end at the upper end thereof. In addition to this tapered arrangement, I provide a recess 14 which extends a greater portion of the dissta'nce lfrom the top of the screw on one side im thereof and a shallowerslo't 16 which'is dis-V posed diametrically opposite the slot 14. The X, slot '16, is merely provided to facilitate the use of a screw driver v(not shown), said screw driver being ada ted to span the central '75 opening or apertu e 12 and to be received by the slots 1 4and 16; f

Particular attention is directed tothe fact that the longer slot 14 facilitates the sghaping or forming of the threaded body o as so to present a substantiallycontinuou's spiral thread surface, which begins at a point designated by the letter A, Figure 1,4 and continues in a counterclockwise direction to a point B. Thus, the point B normally projects outwardly, and when the screw is tightened within a work piece, this point serves as an eilective locking element. The sharpa ness of the point B coupled with the normal tendency for said point to be urged outwardly against thecompanion threaded surface of the work piece, renders the same very efy In Figures 3 and 4 I have shown an alternative forni of screw, which iskdesignated generally by the numeral 10a. This screw 10a differs from the screw 1,0 in that it is formed with a pair of spirally deflected threaded sections 18, which are separated by slots 14a, which correspond with'the slot Hand-the screw 10. The threads in each of the sections 18 being to spiral outwardly from points A1 and continue to the points B1. Thus, it may be stated that substantially the entire length of the threads of the screw serve to frictionally engage the companion surfaces of the threads in the work piece. The only portions of the screw which do not frictionally engage the work piece are those portions which `are eliminated by the presence of the slots 14a.

In ,Figure 5 I have shown a still furthermodiied screw designated vgenerally by the numeral' 10c. This screw differs from the screws just described in Athat it is provided with a slotl 140 extending throughout the.` entire length of the screw body. This screw is spirally formed and slightly tape/red so as to effect the automatic locking of the screw within the work piece.

From the foregoing it will be observed that" by having the spiral arrangement of the thread surfaces, I present a screw which' very effectively andv automatically binds itself v within a work piece, vor, in other words, is. very effectively self-locking. The tapered arrangement ofthe screw facilitates the 'insertion thereof within the work piece and cooperates with the spiral configuration to render the samel very practical. Screws of this type nay be secured in position by the use of an ordinary screw driver or other suitkable device.

In Figure 6 I, have shown a screw designated generally by the numeral 10d.l A plan view of the screw 10d would be similar to the plan view of the screw 1Q shown in Figure 1. However, the screw 10d difl'eisfrom the s crew 10, in that/a central aperture or recess 12dy extends onlyfpartially through the screw, thereby presenting a solidscrew section 20. This solid screw section 20 is of the usual cylindrical cross-section, hereas the portion of the screw extending upwardly from the solid section 2() is formed spirally, as shown in Figure 1.. A slot Mdis provided in the.

screw body to facilitate he spiral forming thereof. The initial cross-section ,of the screw 14d is cylindrical and the laperture'12ai is cylindrical. However, after the portion of the screw above the solid section 2O is spirally formed, as, for example, by a punching operation, the wall' surrounding the aperture or recess 12d and the outer threaded surface of the screw positioned above the solid section 2O assume a tapered form. Spirally forming the screw obviously widens the upper end of the Thus, itwill be apparent that the screw 10d differs from the other screws, iin-that it is' provided with a solid section and a spirally formed sect-ion extending above s aid solid section.

Attention is directed to the fact that the 'taper of the screws with res ect to their axes results from the spiral i orming thereof. Therefore', referring to Figure l, it will be seen thatthe side of the screw 10, which includes the edge A, Figure 1, is parallel with the screw axis. However, iny progressing from the point or eflge A in a counter-clock- Wise direction, it will be seen that the threaded surface of thescrew 10 progressively tapers with respect to the screw axis, said taper progressively increasingy from substantially zero at the point or'edgeA to the point or line of maximum deflection B. The screw 10, as well as the screw 10a, are thus provided with a non-tapering side portion which includes the points or edges A and A', as well as side portions which progressively in-l crease in taper to the points or edges B and'- B. Due to the presence of the slots 14 and 16 of the screw 10, the progressing side taper `:of the screw continues for less than one convolution of the screw thread,.but enables a substantial portion of thel threaded surfaces to frictionally engage the companion threaded surfaces of tliework'piece with which it is associated.v

It should also benoted that the diameterv as the low points of the screw, bearragainstv the companion thread surfaces'of the work piece and thereby provide a support 'to counteract the diametrically opposite force result- 1 ing from the resilient engagement of the screw threads with the work piece. In other words', theforce exerted as ay result of the spiral configuration of the screw is positively counteracted by the engagement of the diametrically opposite portion of the screw with the threads of the work piece. Tlie'locking effectiveness of such a construction will be more apparent when reference is inade to Figure'l, wherein the point of maximum displacement B is shown. IVhcn this .-crew 10 is applied to the work piece, the point l is urged inwardly in conformity with tlnl cylindrical contour of the thi'ear'led opening in the work piece, and the diainotrivally opposite portion of the screw 10 ('fooperates with the threads 65 slot 14d, as clearly shownin the drawing. of .the work piece in providinga support to counteract the inward movement of the point B, and in this manner causes the point B tov be effectively urged into locking relation with the companion surfaces of the work. piece. 5 The same is also true ofthe screw 10a, as

shown in Figure 3, wherein the forces transmitted to or experienced by the points B as the screw is being inserted within a threaded aperture, are counteracted by thev positive engagement of the diametrically opposite portions of the' screw, as, for example, the points A with the companion threadsurfaces of the work piece. l

The structure described above should be clearly distinguished from known types of deflected or offset s'elf-lcking screws, wherein the entire portion of a threaded section of the screw is shifted in order'to position one pdrtion thereof out of the normal cylindrical form of the screw. In these conventional devices the frictional engagement-of the projecting portions 'of the screws are .counteractedJ only bythe resilient connection of the deflected .threaded section of-the screw with the solid end section thereof. In other words, in these conventional devices the frictional engagement of the outwardly projecting portions of the threaded sections of the screw is vnotpositively counteracted by diametrically opposite portions of said threaded sections. In screws of my improved construction, however, the force tending to inwardly urge the projecting portions of the threaded sections, namely, the points B and B shown in Figures 1 and 3, is not only counteractedby the inherent resiliency of the screw body, but is also counteracted by the diametrically `opposite portions ofthe screw body.

l Having thus described my invention, what I claim asnew and desire to secure by Letters Patent is: 1. AA screw including a helically threaded section which is spirally disposed and flexible diametrically to render said screwself-lock'- ing when applied to a work piece. L-

2. A screw including a threaded sectio normally deflected spirally outward`with respect to the Ascrew axis to render the same self-'locking when applied t .a workpiece, said deflected section presenting a substantial length of threadsurface which is adapted to frictionally engage companion 4thread sur? faces of said work piece.

3. A screw includingr -a threaded section greater than one-half of the screw circumference.

5. A screw including a threaded section normally deflected outwardly with respectto the screw axis to render the same self-locking when applied to a work-piece, said deected section presenting a substantial spiral length of thread surface which is adapted to frictionally engage companion thread surfaces of said work piece'and being slightly tapered 'to facilitate the insertion thereof within the aperture of said work piece.

6. A screw including a spirally deflected threaded section whichis adapted to render said screw self-locking when applied to a section.

7. A screw including a spirallyy deflected threadedsection Whichis adapted to render said screw self-locking when applied to a wrk piece, the body of said screw being provided with a pair of oppositely disposed recesses extending longitudinally thereof.

8. -A screw having a centralaperture and a plurality of threaded sections surrounding said aperture, said sections being spirally deilected, whereby the surfaces of the threads of each section -present substantial lengths of thread surfaces which are adapted to frictionall)7 engage companion 'thread surfaces of a work piece.

9. A screw including a threaded section normally deflected outwardly with respect to the'screw axis so as to render the same selflocking when applied to a work piece, the out'- er surface of said threaded section being progressivelytapered with Irespect to the screw f `axis from agiven point'to a' point cof maximum taper. .Y l 10. A screw including a threaded section normally Ideflected outwardlywith respect to scribed my name.' v i CARL G. OLSON.

which is normally deflected spirally outward .i

from a point of substantially zero deflection y on one side of said screw gradually to a point of maximum defiection on 4the oppositg side of said screw, wherebv to render the same self-locking whenapplied to a workpiece.

4. A screw including a threaded section sprung spirally outward from theusual cylindrical screw contour, wherebv to `present a substantial length of thread surface for bind- 65 ing within a work piece, said length being 

